At 13, Thiago Silva ran away from the only home he'd ever known, located just outside of Sao Paulo, Brazil.

Behind, he left his mother, younger brother and abusive father. Leaving home at a young age might sound like a hard thing to do. But according to Silva, it wasn't.

"When you're in a situation where your father hits you and your mother knows but can't do anything about it, there's not really a decision to make," Silva told ESPN.com. "I was going crazy. I wanted out of there. So I ran away."

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Today, Silva is known more for his willingness to take fights than run from them -- but even at an early age, the UFC light heavyweight knew the one with his father couldn't be won. After leaving his immediate family, Silva fled to the poverty-stricken favelas that litter Sao Paulo to live with his grandmother and he didn't look back. He hasn't spoken to his parents or brother in more than a decade.

Silva doesn't like to talk about his past. Doesn't even like thinking about it, really. One might think he could use those memories to push him in his career, but the truth is he'd rather just leave them where they are.

"I live for the present, not the past," he said.

Right now, that present consists of a Jan. 1 meeting with Brandon Vera (11-5) at UFC 125 in Las Vegas. For Silva (14-2), it will be his first fight since dealing with a major back injury earlier this year, which required eight months of physical therapy.

But even though he doesn't like to talk about it, there's no question Silva's past has had a major impact on shaping both the fighter and human being he's become.

After leaving the violent home his father created, Silva found the world he escaped to wasn't much better. Sao Paulo is one of the richest cities in the world but, in contrast, it's notorious for the number of favelas within its limits. The Brazilian slums are known for severe poverty levels, crime and drug trafficking.

Ric Fogel/ESPN.comThiago Silva, left, is looking to bounce back from a loss to Rashad Evans.

"It's a lot different there than the poor places in the United States," Silva said. "The favelas are run by the drug lords. You see people get killed every day but you can't say anything, because then you get killed. It's all about the drugs and the people who are on the drugs will do anything to get them. Sometimes they get killed. That's just the way it is."

When he was 18, Silva finally found refuge from violence in an unlikely place -- mixed martial arts. He met his first mentor, Jorge Macaco, and began training daily. Inside the gym, he found a ticket he knew might lead to a better life. He even found a new friend there, Thaysa, whom he'd eventually marry.

The sport ended up saving his life in more ways than one. Word of his knockout wins, some over opponents weighing as much as 30 pounds more than him, spread to the drug lords and earned their respect. Some of them even sought him out to train their children.

"The violence hit close to me. A lot of my friends died and a lot more went to jail," Silva said. "I didn't have pressure to fall into that type of violence, though, because the drug traffickers liked me. I trained them and I also trained some of their kids."

He made only $300 in his first fights, which he spent on nothing but groceries and vitamin supplements. But by the time he was 23, Silva was making enough to afford an apartment outside of the favelas. Two years later, he signed a contract with the UFC and has since relocated to train with American Top Team in Florida.

Even though he doesn't reflect on it, Silva acknowledges his story is pretty amazing once it's laid out in front of him. He won't go so far as to say he's a hero to the guys back in his old Brazilian gym, but admits many of them look up to him. Every chance he gets, he donates equipment or free apparel he receives from sponsors.

"It's a big conquest," said Silva, on his life. "Back then, I didn't have money to eat or ride the bus. Ninety percent of the people in the favelas don't get out of there. They don't have the opportunity that I have."

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There has been some speculation as to how much longer Silva's opportunity with the UFC will last. Despite winning his first four fights in the organization, Silva has lost two of his past three. A loss to Vera, who is stuck in his own two-fight losing skid, would be a big blow to his standing in the 205-pound division.

At a prefight news conference Wednesday, UFC president Dana White said he wouldn't necessarily cut the loser of the fight and said he's more interested in how each guy comes out.

"What means a lot to me is how they fight Saturday night," White said. "Guys lose in this business, it's how you fight. If they both go for it Saturday night, I can't sit here and tell you that either one of them will be leaving the UFC."

Considering White's answer, Silva's status in the UFC win or lose would appear to be safe. If there's one impact his past has had on his career that's greater than the rest, it's that Silva approaches every fight as a gift.

It's all about the present.

"Where I came from, I suffered. So, I fight with a lot of emotion," Silva said. "Of course I want to win. But after what I've been through and dealing with the back injury, I just can't wait to get in there. I haven't fought in a while. I want a knockout."

Brett Okamoto covers MMA for ESPN.com. Follow him on Twitter at bokamotoESPN.